Cryogenic liquids can be gelled, or in other words converted to a jelly-like material formed by the coagulation of a colloidal particle-laden liquid, by forming a uniform dispersion of finely divided particles of a gelling agent or gelant in the cryogen. A gel can be produced, for example, by mixing steam or other gelant vapor with the cryogen in a manner that allows the cryogen to freeze the steam into an exceedingly fine dispersion of small ice particles. The formation of a gel can facilitate transportation and storage, reduce danger from spills in some situations, and limit absorption of gaseous and other impurities into liquids requiring purity such as liquid rocket propellants.
This invention provides an improved system for gelling cryogenic liquids. The system includes a spray column or other structure for providing a fine spray of cryogenic liquid droplets, a container or vessel for receiving that spray, and an eductive pump for mixing a gelling agent with vapor from the gel container and injecting the resultant mixture into the cryogenic spray. When a superheated gaseous phase flow of gelling agent is supplied to drive the eductive pump, the system provides much improved mixing and produces a high quality uniform gel having a highly dispersed distribution of extremely fine gelant particles. The system can receive a cryogenic liquid to be gelled at a temperature substantially below the saturation temperature of that liquid; this minimizes the gel vaporization or boil-off gas that must ultimately be reliquefied.